Parametric Study of 3D Micro-Fin Tubes on Heat Transfer and Friction Factor

Authors: Shima Soleimani, Steven Eckels

Abstract:

One area of special importance for the surface-level study of heat exchangers is tubes with internal micro-fins (< 0.5 mm tall). Micro-finned surfaces are a kind of extended solid surface in which energy is exchanged with water that acts as the source or sink of energy. Significant performance gains are possible for either shell, tube, or double pipe heat exchangers if the best surfaces are identified. The parametric studies of micro-finned tubes that have appeared in the literature left some key parameters unexplored. Specifically, they ignored three-dimensional (3D) micro-fin configurations, conduction heat transfer in the fins, and conduction in the solid surface below the micro-fins. Thus, this study aimed at implementing a parametric study of 3D micro-finned tubes that considered micro-fine height and discontinuity features. A 3D conductive and convective heat-transfer simulation through coupled solid and periodic fluid domains is applied in a commercial package, ANSYS Fluent 19.1. The simulation is steady-state with turbulent water flow cooling the inner wall of a tube with micro-fins. The simulation utilizes a constant and uniform temperature on the tube outer wall. Performance is mapped for 18 different simulation cases, including a smooth tube using a realizable k-ε turbulence model at a Reynolds number of 48,928. Results compared the performance of 3D tubes with results for the similar two-dimensional (2D) one. Results showed that the micro-fine height has a greater impact on performance factors than discontinuity features in 3D micro-fin tubes. A transformed 3D micro-fin tube can enhance heat transfer, and pressure drops up to 21% and 56% compared to a 2D one, respectfully.

Keywords: Three-dimensional micro-fin tube, heat transfer, friction factor, heat exchanger.

References:

[1] Li, P., 2019. Validation of large eddy simulations for modeling micro-structured enhanced heat transfer surfaces. Ph.D. dissertation, Department of Mechanical and Nuclear Engineering, Kansas State University, USA.
[2] Mann, G.W. and Eckels, S., 2019. Multi-objective heat transfer optimization of 2D helical micro-fins using NSGA-II. International Journal of Heat and Mass Transfer, 132, pp.1250-1261.
[3] Dastmalchi, M., Sheikhzadeh, G.A. and Arefmanesh, A., 2017. Optimization of micro-finned tubes in double pipe heat exchangers using particle swarm algorithm. Applied Thermal Engineering, 119, pp.1-9.
[4] Bhatia, R.S. and Webb, R.L., 2001b. Numerical study of turbulent flow and heat transfer in micro-fin tubes–part 2, parametric study. Journal of Enhanced Heat Transfer, 8(5).
[5] Campet, R., Roy, P.T., Cuenot, B., Riber, É. and Jouhaud, J.C., 2020. Design optimization of a heat exchanger using Gaussian process. International Journal of Heat and Mass Transfer, 150, p.119264.
[6] Webb, R.L., 2009. Single-phase heat transfer, friction, and fouling characteristics of three-dimensional cone roughness in tube flow. International Journal of Heat and Mass Transfer, 52(11-12), pp.2624-2631.
[7] Soleimani, S., Campbel, M. and Eckels, S., 2020. Performance analysis of different transverse and axial micro-fins in a turbulent-flow channel. International Journal of Thermal Sciences, 149, p.106185.
[8] Soleimani, S. and Eckels, S.J., 2019. Effect of Micro-Fin Geometry on Liquid Heat Transfer Rate and Pressure Drop. In ASTFE Digital Library. Begel House Inc.
[9] Brognaux, L.J., Webb, R.L., Chamra, L.M. and Chung, B.Y., 1997. Single-phase heat transfer in micro-fin tubes. International Journal of Heat and Mass Transfer, 40(18), pp.4345-4357.
[10] Takahashi, K., Nakayama, W. and Kuwahara, H., 1988. Enhancement of forced convective heat transfer in tubes having three-dimensional spiral ribs. Heat transfer. Japanese research, 17(4), pp.12-28.
[11] Webb, R.L., Narayanamurthy, R. and Thors, P., 2000. Heat transfer and friction characteristics of internal helical-rib roughness. J. Heat Transfer, 122(1), pp.1.